Drop in Boost

[RossyB]

Guys

First problem ive had with the car, ive currently got a revo stage 1 on my car and went to modify the air box by putting in a new cold air feed still using standard air box, now ever since ive done that my boost has dropped from 20psi to 7 psi.

Ive disconnected battery for half an hour, still the same. Cant see anything under the bonnet that sticks out to be honest.

Any ideas people?

Cheers

 

[cordobabrendy]

sounds like std mode has been initiated, do you know anyone local with an sps device? either that or its running 5psi limp mode, was it deffo 7 psi?
also, did you plug the maf back on if it was disconnected, was it dropped, get it logged with vagcom for a better idea.

 

[-pseudonymous-]

Possibly limp mode? Check the plug to the N75 valve is connected properly.

 

[RossyB]

Ive got a sps3, put the boost on the highest but still the same.

Is that the plug connected the rubber pipe coming off the air box?

 

[Martyn]

Take the air feed off and see if the boost comes back...

 

[-pseudonymous-]

As brendy said check the MAF is plugged in. Thats the plastic unit just before the airbox. The N75 valve is the little 3-way valve just before the Maf sensor. Check thats plugged in also.

 

[RossyB]

Ive checked all plugs pipes cant see anything wrong but will check and try the above cheers.

Im a best just to put standard air feed on, but why has this affected the boost?

 

[Martyn]

Maybe you've created a restriction in the feed to the box.

 

[acidstrato]

checked maf yet?

 

[h17och]

wont be n75 disconnected because if its disconnectd it runs full boost for a while then goes limp

HoocH

 

[Martyn]

If the N75 was either connected incorrectly or not connected electrically you'd only get 5psi....

 

[h17och]

so why when i disconnect mine (electricaly im talking) i get full boost?

 

[Martyn]

Because you're special mate

When the N75 is unplugged (from the ECU) you'll only make 5psi as that's what the WG is set to open at. It's just another of the ECUs failsafes to stop it over boosting if the unit fails.

You may get 'full' boost if you or someone else has adjusted your WG.

 

[Daz_gibbo]

Doubt maf is at fault for such a dramatic loss of boost, should still boost with it unplugged - hence why its worth running with it unplugged when fault finding. Checked all your piping? Probably something silly.
Check your air feed hasn't been sucked into the box. This happened to me once, same symptoms

 

[RossyB]

will check all above guys cheers, looked under bay while had engine running, wiggled the maf about then i heard something to the left of the engine bay clicking in some positions and not in others, what might this be?

pics of N75 valve would be handy guys.

 

[RossyB]

still not solved it, got vagcom on its way to see if it can help and now put standard air feed on.

any other reasons why its still doing it?

 

[Ibiza Cupra]

Mine has done this once before and today!!!! seems like every time i go to brighton my car goes into limp!!!! Drove to Whales and back with no issues, but brighton it just won't do!!!! First time mine done it i done all the obvious things, checked vac hoses, maf, n75 but everything was fine, turned it on and off a few times, disconnected the battery and there wasn't any change. then after about 10 miles come out of a corner and i got plastered in2 the back of my seat!!!! back up to full boost!!!!!

 

[acidstrato]

whales? are you serious dude?

 

[Ibiza Cupra]

whales? are you serious dude?

Yep!!!! It was over 250 miles!!!!! We went to narbeth and temby and saundersfoot!!!! Nice part of the world!!!!

 

[Daz_gibbo]

think he was having a dig at your spelling dude